Turkish President Recep Tayyip Erdogan on Wednesday accused George Soros of aiding a jailed Turkish philanthropist facing hugely controversial charges of seeking to overthrow the government, describing the Hungary-born American billionaire as a "famous Hungarian Jew."

Erdogan suggested Soros had backed the Turkish financier and philanthropist Osman Kavala who organized civil society events and has been in prison for the last year awaiting trial.

In a speech to local officials, Erdogan accused Kavala of financing the 2013 protests over the redevelopment of Gezi Park in Istanbul which at the time marked one of the biggest challenges to his rule.

The file photo shows people during a demonstration on May 31, 2018 in Istanbul to mark the fifth anniversary of the start of the Gezi Park protests. (Photo by AFP)

"There is a person who financed the terrorists in the Gezi events. Now he is behind bars," said Erdogan, referring to Kavala without naming him.

"And who is behind him? The famous Hungarian Jew Soros. This person sends people across the world to divide and tear up nations and uses the large amount of money he possesses to this effect."

George Soros gives a speech on the occasion of the 25th Anniversary of the Open Medical Institute in Vienna, Austria, on November 19, 2018. (Photo by AFP)

He described Kavala as the "representative in Turkey" of Soros and accused Kavala of "using his means to support those trying to tear up this country."

Erdoganís verbal assault against Soros echoed the language of Hungarian Prime Minister Viktor Orban, whose government has implemented a "Stop Soros" package targeting the 88-year-oldís work in his country of birth using imagery that Jewish groups have said could stoke anti-Semitism.

Controversy over the Kavala case has intensified in the last week after 14 Turkish academics and activists were detained on Friday over links to the imprisoned philanthropist.

Those arrests were greeted with strong protests by the United States, European Union and the Turkish opposition.

Kavalaís supporters say his charges of seeking to overthrow the government are absurd and that he had worked tirelessly to build bridges in society, in particular with Armenians.

They also say it is a disgrace he has yet to receive an indictment over a year after his arrest on October 18, 2017.

Erdogan also lashed out at Tuesdayís decision of the European Court of Human Rights to urge the release of pro-Kurdish leader Selahattin Demirtas who has been held for two years on terror charges.

"Make any decision you like in your glass palaces, hold any vote you like. We have never made concessions on our state as democracy governed by rule of law," said Erdogan, accusing Demirtas of inciting October 2014 protests where dozens of mainly Kurdish protesters died.